Hi, it's Dr. Centeno.
And today we're going to focus on new research that
shows that your knee x-ray is probably
pretty useless in diagnosing why your knee hurts,
or at least it's not as valuable as we once thought.
Now, this may come as a complete surprise to you
because x-rays and MRIs are commonly
used by physicians to make the diagnosis of arthritis
and then conclude that that's why the knee hurts.
So if we look at the standard x-ray grading scale,
we can see that it goes from normal to mild
to moderate to severe arthritis on an x-ray.
And it would be very, very attractive
to say that this grading scale equals pain,
meaning the more arthritis you have on the x-ray
the more your knee has to hurt.
Regrettably, a lot of research-- not just the little bit
of research I'll go over here today, but a lot of research--
has shown that that's not the case at all.
So this will look at a new study of the pain marker called NPY.
And the name of the marker isn't really
that important-- NPY is neuralpeptide Y--
but it's just that there is a marker
that you can get out of the knee that correlates well
with knee pain.
And that's the citation of the recent research on this pain
marker.
And what's really interesting is that if you
look at the levels of this pain marker in the knee
there's a very elegant association
between the levels of this pain marker and pain
that people report.
So that's the level if you are healthy.
This is the level if you have some osteoarthritis
but no pain.
This is the level if you have mild pain and knee arthritis.
This is the level if you have moderate pain
and then strong pain and then severe pain.
So you can see this very elegant relationship between the amount
of pain that people are reporting
and the levels of this pain marker in their knee.
On the contrary, though, if we look at the amount of arthritis
that's on an x-ray-- like we just did-- and then track
that versus this pain marker which is directly associated
to how much pain people are reporting, here's what we see.
So that's the amount of pain marker
if there's nothing on the x-ray and then
that's the amount of pain marker if there's
early arthritis and then moderate arthritis.
But we kind of lose the association in severe arthritis
on the x-ray.
In fact, all of this should look like that.
We should see much, much more pain
marker in folks with severe arthritis on their x-ray,
but we're not seeing that.
Now, while this may come as a big surprise to you that
the x-ray isn't all that valuable in correlating with
pain, again, there are numerous other studies that show that
x-rays and MRIs are not that great at predicting who has
knee pain and who doesn't.
So in conclusion, we have to stop
perpetuating the urban myth as physicians
that an x-ray or MRI can readily explain
why someone has knee pain.
This is a 1980s concept.
This is not a concept that holds water in 2014 or 2015.
So again, recognize that this fancy picture
that you got with the fancy radiology report--
whether it was x-ray or an MRI-- doesn't necessarily readily
explain why your knee hurts.
And I know that's hard to wrap your head around
because there's still a lot of positions perpetuating
this urban myth, but it is an urban myth nonetheless.
Thanks for watching.